Sea Service Military Brass Barreled Blunderbuss 1637-45

So I'm walking through an attic with a homeowner. When I spotted this blunderbuss on a stack of boxes. The homeowner informed me that these items in this area would not be moving. He would be disposing of these items before the movers arrived. I inquired about the gun. He informed me that this was a prop from his fathers retail clothing store. He said they use to buy all kinds of thing to use as props in the display windows. The gun had been damaged in a house fire and he just had it cleaned up afterwards so it had just been sitting in the attic for the last 50 yrs.
I made an offer of $100 and the gun was mine. After doing a light cleaning and oiling, I was able to find the Makers Mark and Proof House Stamps on the barrel. 1637 !!!!
The barrel is brass and the lock is bronze, the ram rod is wood with a brass tip. The wood has some charring from the fire but I'm not going to replace any of it.